Ensuring High-quality Canned Foods (part 2 Of Recipe
Yield: 1 GuideRecipe by luhu.jp
Ingredients:
Recipe via Meal-Master (tm) v8.05
Directions:
Advantages of Hot-packing
Many fresh foods contain from 10 percent to more than 30 percent air.
How long canned food retains high quality depends on how much air is
removed from food before jars are sealed.
Raw-packing is the practice of filling jars tightly with freshly
prepared, but unheated food. Such foods, especially fruit, will float
in the jars. The entrapped air in and around the food may cause
discoloration within 2 to 3 months of storage. Raw-packing is more
suitable for vegetables processed in a pressure canner.
Hot-packing is the practice of heating freshly prepared food to
boiling, simmering it 2 to 5 minutes, and promptly filling jars
loosely with the boiled food.
Whether food has been hot-packed or raw-packed, the juice, syrup, or
water to be added to the foods should also be heated to boiling
before adding it to the jars. This practice helps to remove air from
food tissues, shrinks food, helps keep the food from floating in the
jars, increases vacuum in sealed jars, and improves shelf life.
Preshrinking food permits filling more food into each jar.
Hot-packing is the best way to remove air and is the preferred pack
style for foods processed in a boiling-water canner At first, the
color of hot-packed foods may appear no better than that of
raw-packed foods, but within a short storage period, both color and
flavor of hot-packed foods will be superior. Controlling Headspace
The unfilled space above the food in a jar and below its lid is termed
headspace. Directions for canning specify leaving 1/4-inch for jams
and jellies, 1/2-inch for fruits and tomatoes to be processed in
boiling water and from 1- to 1-1/4-inches in low- acid foods to be
processed in a pressure canner This space is needed for expansion of
food as jars are processed, and for forming vacuums in cooled jars.
The extent of expansion is determined by the air content in the food
and by the processing temperature. Air expands greatly when heated to
high temperatures; the higher the temperature, the greater the
expansion. Foods expand less than air when heated.
======================================================= === * USDA
Agriculture Information Bulletin No. 539 (rev. 1994) * Meal-Master
format courtesy of Karen Mintzias
Title: ENSURING SAFE CANNED FOODS (PART 1 OF 2)
Categories: Canning, Information
Yield: 1 Guide
Growth of the bacterium Clostridium botulinum in canned food may cause
botulism--a deadly form of food poisoning. These bacteria exist
either as spores or as vegetative cells. The spores, which are
comparable to plant seeds, can survive harmlessly in soil and water
for many years. When ideal conditions exist for growth, the spores
produce vegetative cells which multiply rapidly and may produce a
deadly toxin within 3 to 4 days of growth in an environment
consisting of:
* a moist, low-acid food * a temperature between 40 degrees F and 120
degrees F * less than 2 percent oxygen
Botulinum spores are on most fresh food surfaces. Because they grow
only in the absence of air, they are harmless on fresh foods.
Most bacteria, yeasts, and molds are difficult to remove from food
surfaces. Washing fresh food reduces their numbers only slightly.
Peeling root crops, underground stem crops, and tomatoes reduces
their numbers greatly. Blanching also helps, but the vital controls
are the method of canning and making sure the recommended
research-based process times, found in these guides, are used.
The processing times in these guides ensure destruction of the largest
expected number of heat-resistant microorganisms in home-canned foods.
Properly sterilized canned food will be free of spoilage if lids seal
and jars are stored below 95 degrees F. Storing jars at 50 degrees F
to 70 degrees F enhances retention of quality.
FOOD ACIDITY AND PROCESSING METHODS
Whether food should be processed in a pressure canner or boiling-water
canner to control botulinum bacteria depends on the acidity in the
food. Acidity may be natural, as in most fruits, or added, as in
pickled food. Low-acid canned foods contain too little acidity to
prevent the growth of these bacteria. Acid foods contain enough
acidity to block their growth, or destroy them more rapidly when
heated The term "pH" is a measure of acidity; the lower its value,
the more acid the food. The acidity level in foods can be increased
by adding lemon juice, citric acid, or vinegar.
Low-acid foods have pH values higher than 4.6. They include red meats,
seafood, poultry, milk, and all fresh vegetables except for most
tomatoes. Most mixtures of low-acid and acid foods also have pH
values above 4.6 unless their recipes include enough lemon juice,
citric acid, or vinegar to make them acid foods. Acid foods have a pH
of 4.6 or lower. They include fruits, pickles, sauerkraut, jams,
jellies, marmalades, and fruit butters.
Although tomatoes usually are considered an acid food, some are now
known to have pH values slightly above 4.6. Figs also have pH values
slightly above 4.6. Therefore, if they are to be canned as acid
foods, these products must be acidified to a pH of 4.6 or lower with
lemon juice or citric acid. Properly acidified tomatoes and figs are
acid foods and can be safely processed in a boiling-water canner.
Botulinum spores are very hard to destroy at boiling-water
temperatures; the higher the canner temperature, the more easily they
are destroyed. Therefore, all low-acid foods should be sterilized at
temperatures of 240 degrees to 250 degrees F, attainable with
pressure canners operated at 10 to 15 PSIG. PSIG means pounds per
square inch of pressure as measured by gauge. The more familiar
"PSIG" designation is used hereafter in this publication. At
temperatures of 240 degrees to 250 degrees F, the time needed to
destroy bacteria in low-acid canned food ranges from 20 to 100
minutes. The exact time depends on the kind of food being canned, the
way it is packed into jars, and the size of jars. The time needed to
safely process low-acid foods in a boiling-water canner ranges from 7
to 11 hours; the time needed to process acid foods in boiling water
varies from 5 to
85 minutes.
PROCESS ADJUSTMENTS AT HIGH ALTITUDES
Using the process time for canning food at sea level may result in
spoilage if you live at altitudes of 1,000 feet or more (Plate 2).
Water boils at lower temperatures as altitude increases. Lower
boiling temperatures are less effective for killing bacteria.
Increasing the process time or canner pressure compensates for lower
boiling temperatures.
Therefore, when following canning directions in this series, select
the proper processing time or canner pressure for the altitude where
you live. If you do not know the altitude, contact your local county
Extension agent. An alternative source of information would be the
local district conservationist with the Soil Conservation Service.
======================================================= === * USDA
Agriculture Information Bulletin No. 539 (rev. 1994) * Meal-Master
format courtesy of Karen Mintzias
Source from luhu.jp
Many fresh foods contain from 10 percent to more than 30 percent air.
How long canned food retains high quality depends on how much air is
removed from food before jars are sealed.
Raw-packing is the practice of filling jars tightly with freshly
prepared, but unheated food. Such foods, especially fruit, will float
in the jars. The entrapped air in and around the food may cause
discoloration within 2 to 3 months of storage. Raw-packing is more
suitable for vegetables processed in a pressure canner.
Hot-packing is the practice of heating freshly prepared food to
boiling, simmering it 2 to 5 minutes, and promptly filling jars
loosely with the boiled food.
Whether food has been hot-packed or raw-packed, the juice, syrup, or
water to be added to the foods should also be heated to boiling
before adding it to the jars. This practice helps to remove air from
food tissues, shrinks food, helps keep the food from floating in the
jars, increases vacuum in sealed jars, and improves shelf life.
Preshrinking food permits filling more food into each jar.
Hot-packing is the best way to remove air and is the preferred pack
style for foods processed in a boiling-water canner At first, the
color of hot-packed foods may appear no better than that of
raw-packed foods, but within a short storage period, both color and
flavor of hot-packed foods will be superior. Controlling Headspace
The unfilled space above the food in a jar and below its lid is termed
headspace. Directions for canning specify leaving 1/4-inch for jams
and jellies, 1/2-inch for fruits and tomatoes to be processed in
boiling water and from 1- to 1-1/4-inches in low- acid foods to be
processed in a pressure canner This space is needed for expansion of
food as jars are processed, and for forming vacuums in cooled jars.
The extent of expansion is determined by the air content in the food
and by the processing temperature. Air expands greatly when heated to
high temperatures; the higher the temperature, the greater the
expansion. Foods expand less than air when heated.
======================================================= === * USDA
Agriculture Information Bulletin No. 539 (rev. 1994) * Meal-Master
format courtesy of Karen Mintzias
Title: ENSURING SAFE CANNED FOODS (PART 1 OF 2)
Categories: Canning, Information
Yield: 1 Guide
Growth of the bacterium Clostridium botulinum in canned food may cause
botulism--a deadly form of food poisoning. These bacteria exist
either as spores or as vegetative cells. The spores, which are
comparable to plant seeds, can survive harmlessly in soil and water
for many years. When ideal conditions exist for growth, the spores
produce vegetative cells which multiply rapidly and may produce a
deadly toxin within 3 to 4 days of growth in an environment
consisting of:
* a moist, low-acid food * a temperature between 40 degrees F and 120
degrees F * less than 2 percent oxygen
Botulinum spores are on most fresh food surfaces. Because they grow
only in the absence of air, they are harmless on fresh foods.
Most bacteria, yeasts, and molds are difficult to remove from food
surfaces. Washing fresh food reduces their numbers only slightly.
Peeling root crops, underground stem crops, and tomatoes reduces
their numbers greatly. Blanching also helps, but the vital controls
are the method of canning and making sure the recommended
research-based process times, found in these guides, are used.
The processing times in these guides ensure destruction of the largest
expected number of heat-resistant microorganisms in home-canned foods.
Properly sterilized canned food will be free of spoilage if lids seal
and jars are stored below 95 degrees F. Storing jars at 50 degrees F
to 70 degrees F enhances retention of quality.
FOOD ACIDITY AND PROCESSING METHODS
Whether food should be processed in a pressure canner or boiling-water
canner to control botulinum bacteria depends on the acidity in the
food. Acidity may be natural, as in most fruits, or added, as in
pickled food. Low-acid canned foods contain too little acidity to
prevent the growth of these bacteria. Acid foods contain enough
acidity to block their growth, or destroy them more rapidly when
heated The term "pH" is a measure of acidity; the lower its value,
the more acid the food. The acidity level in foods can be increased
by adding lemon juice, citric acid, or vinegar.
Low-acid foods have pH values higher than 4.6. They include red meats,
seafood, poultry, milk, and all fresh vegetables except for most
tomatoes. Most mixtures of low-acid and acid foods also have pH
values above 4.6 unless their recipes include enough lemon juice,
citric acid, or vinegar to make them acid foods. Acid foods have a pH
of 4.6 or lower. They include fruits, pickles, sauerkraut, jams,
jellies, marmalades, and fruit butters.
Although tomatoes usually are considered an acid food, some are now
known to have pH values slightly above 4.6. Figs also have pH values
slightly above 4.6. Therefore, if they are to be canned as acid
foods, these products must be acidified to a pH of 4.6 or lower with
lemon juice or citric acid. Properly acidified tomatoes and figs are
acid foods and can be safely processed in a boiling-water canner.
Botulinum spores are very hard to destroy at boiling-water
temperatures; the higher the canner temperature, the more easily they
are destroyed. Therefore, all low-acid foods should be sterilized at
temperatures of 240 degrees to 250 degrees F, attainable with
pressure canners operated at 10 to 15 PSIG. PSIG means pounds per
square inch of pressure as measured by gauge. The more familiar
"PSIG" designation is used hereafter in this publication. At
temperatures of 240 degrees to 250 degrees F, the time needed to
destroy bacteria in low-acid canned food ranges from 20 to 100
minutes. The exact time depends on the kind of food being canned, the
way it is packed into jars, and the size of jars. The time needed to
safely process low-acid foods in a boiling-water canner ranges from 7
to 11 hours; the time needed to process acid foods in boiling water
varies from 5 to
85 minutes.
PROCESS ADJUSTMENTS AT HIGH ALTITUDES
Using the process time for canning food at sea level may result in
spoilage if you live at altitudes of 1,000 feet or more (Plate 2).
Water boils at lower temperatures as altitude increases. Lower
boiling temperatures are less effective for killing bacteria.
Increasing the process time or canner pressure compensates for lower
boiling temperatures.
Therefore, when following canning directions in this series, select
the proper processing time or canner pressure for the altitude where
you live. If you do not know the altitude, contact your local county
Extension agent. An alternative source of information would be the
local district conservationist with the Soil Conservation Service.
======================================================= === * USDA
Agriculture Information Bulletin No. 539 (rev. 1994) * Meal-Master
format courtesy of Karen Mintzias
Source from luhu.jp